Invasive species have long been identified by conservationists as one of the greatest threats to biodiversity. When introduced to natural ecosystems, invasive species can degrade habitats or harm native animals by preying on them or their prey.

However, a number of recent articles in influential scientific journals have questioned the urgency of addressing the threat to biodiversity from invasive species, amid concerns that conservationists may not be making the necessary distinction between invasive species and alien species in their desire to maintain pristine ecosystems.

The brown rat (Rattus norvegicus) has been the cause of many extinctions worldwide, particularly seabirds restricted to remote, predator-free islands.

Alien species are introduced outside their natural range by humans, and are in many cases harmless. Invasive species on the other hand, are not only introduced outside their range, but also cause substantial harm to biodiversity and human livelihoods.

In certain cases, alien species may prove beneficial to human wellbeing. Examples include the honey bee, which has been introduced to North America, and various crops such as corn and potato which were introduced to Europe and have become staple dietary components for millions of people.

Invasive species, not alien species, are however a major cause of biodiversity loss, and are implicated in the majority of extinctions recorded to date.

To counter the concerns raised by some of the recent articles, a letter recently published in Science magazine aims to highlight the growing threat to biodiversity from invasive species, and addresses some of the dangerous misunderstandings of the issue.

The Cuban treefrog (Osteopilus septentrionalis) has been introduced to numerous Caribbean islands outside its native Cuba, and is preying on many rare amphibians.

The letterargues that the concerns raised over tackling the invasive species problem are unfounded, and that conservationists do recognise a clear distinction between alien species and invasive species.

The authors highlight that threats from invasive species can be reduced, and that biodiversity can be protected through carefully targeted conservation interventions.

The honey bee has been beneficial to humans by providing food and pollinating crops.

“Tackling invasive species also addresses the economic damage they cause and the serious threats that they pose to human health and livelihoods,” says Julia Marton-Lefèvre.

“Attempts to remove the most harmful invasive species are proving to be increasingly successful, with more than 1,000 eradications completed worldwide to date.”

In speaking out and making clear the distinction between invasive and alien species, the authors of the letter have demonstrated their commitment to the fight against invasive species, and now call upon academics for support and, above all, action.

“Invasive species, not alien species, are however a major cause of biodiversity loss, and are implicated in the majority of extinctions recorded to date.”

Really? Surely the most destructive species of them all, one that spread out of Africa, has destroyed more habitats and caused more extinctions than all other ‘invasive’ species put together? After all, it’s us that’s spread most of the really damaging invasives like rats, pigs, cats, mongooses etc – it’s not even as if we are just ‘implicated: we’re definitely responsible?

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